Handle "p S::method()::static_var" in the C++ parser

This commit makes "print S::method()::static_var" actually find the
debug symbol for static_var.  Currently, you get:

  (gdb) print S::method()::static_var
  A syntax error in expression, near `'.

Quoting the whole string would seemingly work before the previous
patch that made GDB stop assuming int for no-debug-info variables:

  (gdb) p 'S::method()::static_var'
  $1 = 1

... except that's incorrect output, because:

  (gdb) ptype 'S::method()::static_var'
  type = <data variable, no debug info>

The way to make it work correctly currently is by quoting the
function/method part, like this:

  (gdb) print 'S::method()'::static_var
  $1 = {i1 = 1, i2 = 2, i3 = 3}
  (gdb) ptype 'S::method()'::static_var
  type = struct aggregate {
      int i1;
      int i2;
      int i3;
  }

At least after the "stop assuming int" patch, this is what we
now get:

  (gdb) p 'S::method()::static_var'
  'S::method()::static_var' has unknown type; cast it to its declared type
  (gdb) p (struct aggregate) 'S::method()::static_var'
  $1 = {i1 = 1, i2 = 2, i3 = 3}

However, IMO, users shouldn't really have to care about any of this.
GDB should Just Work, without quoting, IMO.

So here's a patch that implements support for that in the C++ parser.
With this patch, you now get:

  (gdb) p S::method()::S_M_s_var_aggregate
  $1 = {i1 = 1, i2 = 2, i3 = 3}
  (gdb) ptype S::method()::S_M_s_var_aggregate
  type = struct aggregate {
      int i1;
      int i2;
      int i3;
  }

gdb/ChangeLog:
2017-09-04  Pedro Alves  <palves@redhat.com>

	(%type <voidval>): Add function_method.
	* c-exp.y (exp): New production for calls with no arguments.
	(function_method, function_method_void_or_typelist): New
	productions.
	(exp): New production for "method()::static_var".
	* eval.c (evaluate_subexp_standard): Handle OP_FUNC_STATIC_VAR.
	* expprint.c (print_subexp_standard, dump_subexp_body_standard):
	Handle OP_FUNC_STATIC_VAR.
	* parse.c (operator_length_standard):
	Handle OP_FUNC_STATIC_VAR.
	* std-operator.def (OP_FUNC_STATIC_VAR): New.

gdb/testsuite/ChangeLog:
2017-09-04  Pedro Alves  <palves@redhat.com>

	* gdb.base/local-static.c: New.
	* gdb.base/local-static.cc: New.
	* gdb.base/local-static.exp:  New.

1 files changed, 41 insertions, 2 deletions

diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index a1f9fee..f7f098b 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -127,7 +127,7 @@ static void c_print_token (FILE *file, int type, YYSTYPE value);
 #endif
 %}
 
-%type <voidval> exp exp1 type_exp start variable qualified_name lcurly
+%type <voidval> exp exp1 type_exp start variable qualified_name lcurly function_method
 %type <lval> rcurly
 %type <tval> type typebase
 %type <tvec> nonempty_typelist func_mod parameter_typelist
@@ -498,6 +498,18 @@ exp	:	exp '('
 			  write_exp_elt_opcode (pstate, OP_FUNCALL); }
 	;
 
+/* This is here to disambiguate with the production for
+   "func()::static_var" further below, which uses
+   function_method_void.  */
+exp	:	exp '(' ')' %prec ARROW
+			{ start_arglist ();
+			  write_exp_elt_opcode (pstate, OP_FUNCALL);
+			  write_exp_elt_longcst (pstate,
+						 (LONGEST) end_arglist ());
+			  write_exp_elt_opcode (pstate, OP_FUNCALL); }
+	;
+
+
 exp	:	UNKNOWN_CPP_NAME '('
 			{
 			  /* This could potentially be a an argument defined
@@ -539,7 +551,7 @@ arglist	:	arglist ',' exp   %prec ABOVE_COMMA
 			{ arglist_len++; }
 	;
 
-exp     :       exp '(' parameter_typelist ')' const_or_volatile
+function_method:       exp '(' parameter_typelist ')' const_or_volatile
 			{ int i;
 			  VEC (type_ptr) *type_list = $3;
 			  struct type *type_elt;
@@ -557,6 +569,33 @@ exp     :       exp '(' parameter_typelist ')' const_or_volatile
 			}
 	;
 
+function_method_void:	    exp '(' ')' const_or_volatile
+		       { write_exp_elt_opcode (pstate, TYPE_INSTANCE);
+			 write_exp_elt_longcst (pstate, 0);
+			 write_exp_elt_longcst (pstate, 0);
+			 write_exp_elt_opcode (pstate, TYPE_INSTANCE);
+		       }
+       ;
+
+exp     :       function_method
+	;
+
+/* Normally we must interpret "func()" as a function call, instead of
+   a type.  The user needs to write func(void) to disambiguate.
+   However, in the "func()::static_var" case, there's no
+   ambiguity.  */
+function_method_void_or_typelist: function_method
+	|               function_method_void
+	;
+
+exp     :       function_method_void_or_typelist COLONCOLON name
+			{
+			  write_exp_elt_opcode (pstate, OP_FUNC_STATIC_VAR);
+			  write_exp_string (pstate, $3);
+			  write_exp_elt_opcode (pstate, OP_FUNC_STATIC_VAR);
+			}
+	;
+
 rcurly	:	'}'
 			{ $$ = end_arglist () - 1; }
 	;